# std::chrono::operator<<(std::chrono::year)

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< cpp‎ | chrono‎ | year

Defined in header `<chrono>` |  |
template< class CharT, class Traits > std::basic_ostream<CharT, Traits>& operator<<( std::basic_ostream<CharT, Traits>& os, const std::chrono::year& y ); |  | (since C++20)

Forms a std::basic_string<CharT> s consisting of the year value stored in y formatted as a decimal number, left-padded with ​0​ to four digits if the result would otherwise be less than four digits. Then, if !y.ok(), append " is not a valid year" to the formatted string. Inserts that string into os.

Equivalent to

return os << (y.ok() ?
std::format(STATICALLY_WIDEN<CharT>("{:%Y}"), y) :
std::format(STATICALLY_WIDEN<CharT>("{:%Y} is not a valid year"), y));

where STATICALLY_WIDEN<CharT>("...") is "..." if `CharT` is `char`, and L"..." if `CharT` is `wchar_t`.

### Return value

os

### Example

Run this code

    #include <chrono>
    #include <iostream>

    int main()
    {
        constexpr std::chrono::year y1{2020}, y2{-020}, y3{98304};
        std::cout << y1 << '\n'
                  << y2 << '\n'
                  << y3 << '\n';
    }

Possible output:

    2020
    -0016
    -32768 is not a valid year

### See also

format (C++20) | stores formatted representation of the arguments in a new string (function template)
std::formatter<std::chrono::year> (C++20) | formatting support for `year` (class template specialization)

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